Actuating mechanism

ABSTRACT

A device, having a planetary gear and a single motor, in use for switching and transmitting a driving force of the motor to any one of station gears and for driving each station gear in both rotational directions. The operation of locking levers for preventing a planetary gear from revolving around a sun gear is controlled by a cam. The cam is actuated by a driving force of the motor. A spring frictionally connecting the cam and an output shaft of a speed reduction system is interposed therebetween, and a magnet is disposed so as to restrict the movement of the cam when the motor rotates. A sun gear is connected with the output shaft of the speed reduction system with a &#34;play&#34; or gap in order that the rotation of the sun gear is reversed behind time corresponding to the play when the rotation of the motor is reversed, thus making it possible to start actuating the cam earlier than the sun gear for making sure that the locking levers are shifted.

This application is a divisional of Ser. No. 08/586,480, filed on Jan.16, 1996, now U.S. Pat. No. 5,697,263, which, in turn, is a continuationof Ser. No. 08/175,307, filed on Dec. 29, 1993, now abandoned.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention generally relates to an actuating mechanism ableto accomplish a plurality of different works independently by theoperation of a single motor, and particularly relates to the actuatingmechanism for switching and transmitting a driving force to a desiredmechanism provided in a camera.

2. Description of the Related Arts

Conventionally, there have been provided some types of actuatingmechanisms. Taking actuating mechanisms shown in Japanese Laid-OpenPatent (Unexamined) Publication Nos. 1-287648 and 3-208033 (FIGS. 8-11in particular) for examples, a sun gear is connected to an output shaftof a motor, planetary gears are revolved around the sun gear, and adriving force can be switched and transmitted to any desired one ofdriving stations via one of the planetary gears.

In the former conventional art, a plurality of planetary gears isprovided in one-to-one correspondence to respective station gears;namely, there are provided planetary gears equal in number to thestation gears. Furthermore, the actuating mechanism is constructed sothat one rotational direction of the motor makes each planetary gearrevolve, while the other rotational direction thereof makes eachplanetary gear rotate on its axis. Accordingly, it is only in onedirection that each planetary gear can rotate on its axis, and it is notpossible to transmit to each station gear the driving force enabling itto rotate in both directions.

In the latter conventional art, it is possible to drive each stationgear in both rotational directions, because the revolution of oneplanetary gear can lead to switching from one station gear to another,and because the movement of its planetary carrier is restrained with theplanetary gear engaging the station gear. However, because the restraintor unrestraint of the planetary carrier with respect to each stationgear is performed by using a driving source different from one fordriving the actuating mechanism itself, and because a large power isrequired to move the restraining member on which a load due to thedriving is imposed and to overcome its friction, a large and expensiveplunger must be used in the actuating mechanism. Employing such a largeand expensive plunger acts as a disadvantage in providing a smaller andcheaper actuating mechanism.

SUMMARY OF THE INVENTION

It is accordingly an object of the present invention to provide acompact and inexpensive actuating mechanism by using a simple and lessexpensive magnet instead of a large-scale plunger, in which each desiredstation gear can be driven in both rotational directions.

In accomplishing this and other objects of the present invention, thereis provided an actuating mechanism comprising: a driving source with adriving shaft able to rotate in both rotational directions; a sun geardriven by the driving shaft; a planetary gear, engaging with the sungear, which can select either condition from a first condition in whichit revolves around the sun gear and a second condition in which itrotates on its axis at a desired position along an orbital path takenaround the sun gear; at least one transmission gear, located along theorbital path of the planetary gear, which can engage with the planetarygear; first control means for switching between a first state in whichthe planetary gear is allowed only to rotate on its axis but is notallowed to revolve around the sun gear and a second state in which theplanetary gear is allowed to revolve around the sun gear; second controlmeans, driven by the driving shaft, for switching the first controlmeans between the first and second state; and a magnet for switching thesecond control means between a condition in which a movement of thesecond control means is restrained and a condition in which the movementthereof is not restrained, in order to keep the first control means ineither state selected from the first and second state.

According to the above mechanism, the planetary gear switches andtransmits the driving force of the driving source to a desiredtransmission gear by which each particular system is actuated. Thedriving source is used, for example, is a motor rotatable in tworotational directions. When the planetary gear gets the driving forcefrom the driving source via the sun gear, and it rotates on its axis,the desired transmission gear is driven by receiving the driving force.In transmitting the driving force, if the sun gear rotates, for example,clockwise, the planetary gear also starts revolving clockwise around thesun gear. Accordingly, unless the planetary gear rotates on its axiswith its revolution around the sun gear being prevented, it is notpossible to keep transmitting the driving force to the particulartransmission gear. The first control means prevents the planetary gearfrom revolving round the sun gear when the driving force is transmittedto the transmission gear, whereas the first control means allows theplanetary gear to revolve round the sun gear when the transmission gearis switched from one to another. The timing of the movement of the firstcontrol means is controlled by the second control means which isactuated by receiving the driving force from the driving source. Thatis, the driving source for driving the planetary gear is used as thedriving source for driving the second control means. The magnetrestricts the movement of the second control means by magneticallyattracting the second control means when the shaft of the driving sourceis rotating, whereas the magnet releases the movement of the secondcontrol means in case of operating the second control means. The magnetis smaller and more inexpensive than a plunger device, thus making theactuating mechanism smaller and manufactured at a lower cost.

In the above mechanism, frictional connecting means can be providedbetween the driving shaft and the second control means. Under theconstruction, the frictional connecting means slips when the movement ofthe second control means is restrained, thus preventing the drivingforce from being transmitted from the driving source to the secondcontrol means, whereas the frictional connecting means transmits thedriving force to the second control means when the movement of thecontrol means is not restrained.

Preferably, the sun gear is connected to the driving shaft of thedriving source with a predetermined play or gap, by which the sun gearis driven behind time corresponding to the play when the rotationaldirection of the driving shaft is changed. According to this mechanism,the driving force is not transmitted to the sun gear, the planetary gearor the transmission gear until the sun gear starts to reverse itsrotational direction. In other words, the second control means neverfails to start moving earlier than the sun gear, and the first controlmeans is actuated when the sun gear and the planetary gear are free fromthe driving shaft.

Between the driving shaft and the sun gear is provided a speed-reductionsystem. By employing a planetary gear train for the speed-reductionsystem, and by integrating its peripheral ring gear and the secondcontrol means, it is possible to simplify the actuating mechanism inconstruction.

The driving force of the driving source can be utilized to drive thesecond control means or to drive the sun gear by limiting the movementof the peripheral ring gear to a certain range. That is, when themovement of the peripheral ring gear is restricted, the sun gear isdriven, because the driving load of the ring gear with respect to thedriving source is immense in magnitude. On the other hand, when thedriving load of the sun gear is larger than that of the peripheral ringgear within limit that the ring gear can rotate, the ring gear or thesecond control means is actuated.

BRIEF DESCRIPTION OF THE DRAWINGS

This and other objects and features of the present invention will becomeclear from the following description taken in conjunction with thepreferred embodiments thereof with reference to the accompanyingdrawings, in which:

FIG. 1 is an explanatory bottom view showing an actuating mechanismaccording to a first embodiment of the present invention;

FIG. 2 is a vertical sectional view of the actuating mechanism shown inFIG. 1;

FIG. 3 is an explanatory bottom view of the actuating mechanism shown inFIG. 1 in which a film is being wound at a high speed;

FIG. 4 is an explanatory bottom view of the actuating mechanism shown inFIG. 1 in which the film is being wound at a low speed;

FIG. 5 is an explanatory bottom view of the actuating mechanism shown inFIG. 1 in which the film is being rewound;

FIG. 6 is an explanatory bottom view of the actuating mechanism shown inFIG. 1 in which zooming operation is performed;

FIG. 7 is an explanatory bottom view of the actuating mechanism shown inFIG. 1 in which zooming operation is performed;

FIG. 8 is an explanatory bottom view of the actuating mechanism shown inFIG. 1 in which a planetary gear is rotating clockwise to switch thestation;

FIG. 9 is an explanatory bottom view of the actuating mechanism shown inFIG. 1 in which a planetary gear is rotating counter clockwise to switchthe station;

FIG. 10 is an explanatory bottom view of the actuating mechanism shownin FIG. 1 in which a planetary gear is rotating clockwise to switch thestation;

FIG. 11 is an explanatory view showing the construction of a spool locklever and a cam surface provided on a planetary carrier of the actuatingmechanism shown in FIG. 1;

FIG. 12 is an explanatory view showing the relationship between thespool locking lever, the cam surface both of which are shown in FIG. 11,and a station gear;

FIG. 13 is an explanatory view similar to FIG. 12;

FIG. 14 is a transverse sectional view showing the construction of a"play connection" between an output of a speed reduction system and thesun gear of the actuating mechanism shown in FIG. 1;

FIG. 15 is an explanatory bottom view showing an actuating mechanismaccording to a second embodiment of the present invention;

FIG. 16 is a vertical sectional view of the actuating mechanism shown inFIG. 15;

FIG. 17 is an explanatory bottom view of the actuating mechanism shownin FIG. 15 in which a film is being wound;

FIG. 18 is an explanatory bottom view of the actuating mechanism shownin FIG. 15 in which a planetary gear is rotating clockwise to switch thestation;

FIG. 19 is an explanatory bottom view of the actuating mechanism shownin FIG. 15 in which zooming operation is performed;

FIG. 20 is an explanatory bottom view of the actuating mechanism shownin FIG. 15 in which zooming operation is performed;

FIG. 21 is an explanatory bottom view of the actuating mechanism shownin FIG. 15 in which the film is being rewound;

FIG. 22 is an explanatory bottom view of the actuating mechanism shownin FIG. 15 in which the rotational direction of a motor is reversed anda magnet is energized in order to switch the station;

FIG. 23 is an explanatory bottom view of the actuating mechanism shownin FIG. 15 in which a switch is turned on when the planetary gear passesa station gear;

FIG. 24 is an explanatory bottom view similar to FIG. 23;

FIG. 25 is an explanatory bottom view of the actuating mechanism of FIG.15 which shows the state thereof immediately after the actuatingmechanism is shifted to the state shown in FIG. 17;

FIG. 26 is an explanatory view showing an actuating mechanism accordingto a third embodiment of the present invention;

FIG. 27 is a vertical sectional view showing the actuating mechanismshown in FIG. 26;

FIG. 28 is an explanatory view showing a forward drive state of theactuating mechanism of FIG. 26;

FIG. 29 is an explanatory view showing a ring gear charge state of theactuating mechanism of FIG. 26;

FIG. 30 is an explanatory view showing a backward drive state of theactuating mechanism of FIG. 26;

FIG. 31 is an explanatory view showing a modification of the actuatingmechanism, according to the present invention, in which any one ofstation gears can be driven to rotate only in one rotational direction;

FIG. 32 is a front view showing the relationship between the actuatingmechanism of FIG. 15 and a camera;

FIG. 33 is an explanatory view showing a differential mechanism providedin the actuating mechanism of FIG. 26;

FIG. 34 is a front view showing the relationship between the actuatingmechanism of FIG. 1 and the camera;

FIG. 35 is a bottom view showing the relationship between the actuatingmechanism of FIG. 1 and the camera; and

FIG. 36 is a bottom view showing the relationship between the actuatingmechanism of FIG. 15 and the camera.

DETAILED DESCRIPTION OF THE INVENTION

Before the description of the present invention proceeds, it is to benoted that like parts are designated by like reference numeralsthroughout the accompanying drawings.

FIG. 1 is an explanatory view showing an actuating mechanism accordingto a first embodiment of the present invention, which is viewed from thebottom of a camera, and FIG. 2 is a vertical sectional view showing theactuating mechanism of FIG. 1. A major portion of the actuatingmechanism is disposed inside and below a film take-up spool 101. Thespool 101 will be referred as camera-spool 101 or, simply, spool 101,hereinafter. A motor 102 serving as a driving source is accommodatedinside the spool 101. The output shaft projecting downward of the motor102 is connected with a speed-reduction system 103 which comprises atrain of planetary gears disposed in two-stage vertically. There isprovided, on an output shaft 104 of the speed-reduction system 103, aplanetary gear mechanism serving as a switching mechanism for switchingone driving force to different station gears, each of which constitutesa driving force transmitting system according to the present embodiment.The planetary gear mechanism comprises a sun gear 105, a planetary gear106 engaging the sun gear 105 and a carrier 107 on which the planetarygear 106 is installed via a spring 108 as shown in FIG. 2. Friction isgenerated between the planetary gear 106 and the carrier 107;accordingly, the planetary gear 106 rotates round the sun gear 105unless a rotation-preventing force is exerted upon the carrier 107. Therotation of the planetary gear 106 around the sun gear 105 makes itpossible to switch one driving force to different station gears in thedriving force transmitting system. When the sun gear 105 rotates with acondition that the rotation of the planetary gear 106 around the sungear 105 is prohibited, the planetary gear 106 rotates on its axis,transmitting its rotation to the driving force transmitting system. Theplanetary gear 106 can rotate on its axis both clockwise andcounterclockwise, enabling to make the driving force transmitting systemperform two kinds of operations as will be described later.

Station gears 109₁ -109₄ are disposed along the orbit of the planetarygear 106 so that the station gears 109₁ -109₄ serve as input terminalsfor transmitting the driving force from the motor 102 via the sun gear105 and the planetary gear 106 to a mechanism for winding a film, amechanism for rewinding the film, a mechanism for moving photographinglens back and forth, and other mechanisms.

This camera has the actuating mechanism in which the spool 101 can berotated in a low speed driving mode and a normal speed driving (highspeed) mode. The low speed mode thereof is selected when it is necessaryto transmit the driving force of the motor 102 to the spool 101 at alarge speed-reduction ratio. This low speed mode is selected in windingthe film, for example, when the output voltage of the power sourcedriving the motor 102 starts dropping down, when temperature is low, orwhen it is necessary to feed out the film from a film cartridge with abigger fiction force. Referring to FIGS. 3 and 4, the driving force fromthe motor 102 is transmitted via the station gear 109₁ or 109₄ to aspool gear 101a formed on the peripheral surface of the lower endportion of the spool 101. The station gear 109₁ is a first spool-drivinggear for rotating the spool 101 at a high speed, whereas the stationgear 109₄ is a second spool-driving gear for rotating the spool 101 at alow speed. The station gear 109₄ is constructed to be a double-gear forspeed reduction. In this construction, the planetary gear 106 engagesits larger gear of the station gear 109₄ or disengages therefrom, and asmaller gear of the station gear 109₄ is always in engagement with thespool gear 101a. The station gears 109₁ and 109₄ are disposed at bothends of the group gears 109₁ -109₄ around the sun gear 105 as shown inFIG. 1.

In the gear mechanism for driving the spool 101, the driving force fromthe motor 102 is transmitted to the spool gear 101a via the sun gear 105installed on the output shaft 104 of the speed-reduction system 103, theplanetary gear 106, and the station gear 109₁ or 109₄. As shown in FIG.2, an internal ring gear 101b is formed on the inner surface of thelower end of the spool 101. This functions as a peripheral side gear ofthe speed-reduction system 103 with respect to three planetary gearsdisposed vertically in triple-stair. That is, the internal ring gear101b is not a gear fixed, but a gear rotatable. The speed-reductionsystem 103 thus comprising the planetary gear train and rotatable ringgear is able to provide a greater speed-reduction ratio than aspeed-reduction gear system comprising gears having the same number ofteeth and a fixed ring gear. In addition, the speed-reduction system 103can be accommodated inside the spool 101, thus allowing the camera to beshorter and compact. In a conventional speed-reduction gear systemhaving a fixed ring gear, in order to accommodate the fixed ring gearinside a spool, it is required to make the diameter of the fixed ringgear smaller than that of the rotatable ring gear according to thepresent embodiment by the thickness of the fixed ring gear, namely, tomake the speed-reduction gear ratio smaller or to make the diameter ofthe spool larger.

The station gear 109₂ transmits the driving force from the motor 102 toa film-rewinding system 124. In the state that the planetary gear 106engages the station gear 109₂, the planetary gear 106 also engages thestation gear 109₁. As a result, the spool 101 is driven at a high speedboth in film-winding and film-rewinding directions. As shown in FIGS. 3and 5, a clutch mechanism constructed from another planetary gearmechanism PG is installed in the camera, by which only when the film isrewound, i.e., when the planetary gear 106 rotates clockwise on itsaxis, the driving force from the motor 102 is transmitted to thefilm-rewinding system 124. The gear train of the film-rewinding system124 is shown in FIGS. 34 and 35. Reference numeral 140 denotes a filmcartridge, and 141 denotes a gear connected with a fork (not shown) fordriving the spool of the cartridge 140.

Generally, as regards the type of a camera in which a film tension isreleased by loosening the film winding on a camera-spool when rewindingthe film by driving both the camera-spool and a cartridge-spool,conditions that the speed-reduction ratio in the rewinding system mustsatisfy are the following two conditions:

(a) a first condition under which it is possible to rewind the film evenif the power output of the battery for driving the motor drops down,even if the camera is used under a low-temperature environment, even ifthe resistance to rewinding the film is larger, etc., and

(b) a second condition that the speed of the film fed out from thecamera spool is larger than the speed of the film wound around thecartridge-spool. Generally, because larger speed-reduction ratio isrequired in condition (b) than in condition (a), the speed-reductionratio meeting the condition (b) is necessarily applied to the rewindingsystem installed in the conventional camera. This means that the speedof rewinding the film is slower than that which can be achieved by themotor. According to the embodiment of the present invention, however,the film-rewinding mechanism has two rewinding modes as mentioned above;therefore, it is possible to rotate the camera-spool 101 faster than thecartridge-spool. Consequently, even if the speed-reduction ratio is setin accordance with the abovementioned condition (a), the condition (b)is satisfied, because the camera-spool is rotating faster than thecartridge-spool. In other words, this camera has an ability ofhigh-speed film rewinding.

The station gear 109₃ transmits the driving force from the motor 102 toa driving system for moving a photographic lens barrel 122 back andforth along the optical axis. A pair of screw gears 121a and 121b isinterposed between the station gear 109₃, and a gear 120 (see FIG. 2)formed on a rotary ring disposed round the periphery of the lens barrel122. The rotational axes of the screw gears 121a and 121b aredifferentiated by 90° from each other. The speed-reduction ratio betweenthe screw gears 121a and 121b is set to a value required for performingzooming operation. Under the state in which the planetary gear 106 is inengagement with the station gear 109₃, when the planetary gear 106rotates clockwise on its axis, zooming operation is switched fromtelescopic side to wide side, whereas when the planetary gear 106rotates counterclockwise on its axis, zooming operation is switched fromthe wide side to the telescopic side as shown in FIG. 6 or 7. In anycase, a locking lever 111₁ or 111₂ prevents the rotation of the carrier107 so as to prevent the planetary gear 106 from rotating round the sungear 105, as will be described later.

In the actuating mechanism, according to the embodiment, adopted in acamera of a type in which zooming operation is performed, backlash isgot rid of by rotating the planetary gear 106 in the same directionbefore stopping in zooming operation. More specifically, for example, ifit is constructed such that the lens barrel is moved from the wide sideto the telescopic side, to prevent the lens barrel movement from thetelescopic side to the wide side, the planetary gear 106 is rotated alittle bit in such a rotational direction that the lens barrel is movedfrom the wide side to the telescopic side before stopping. Similarly, ifit is constructed such that the lens barrel is moved from the telescopicside to the wide side, to prevent the lens barrel movement from the wideside to the telescopic side, the planetary gear 106 is rotated a littlebit in such a rotational direction that the lens barrel is moved fromthe telescopic side to the wide side before stopping. In any case, whenzooming operation is completed, the positional relationship between theplanetary gear 106 and the station gear 109₃ is as shown in FIG. 7. Inthis state, the film can be wound at any time. That is, in winding thefilm at a high speed after the shutter is released, the positionalrelationship between the planetary gear 106 and the station gear 109₃ ischanged from the state shown in FIG. 7 to that shown in FIG. 3 via thestates shown in FIGS. 9 and 5. In winding the film at a low speed afterthe shutter is released, the positional relationship between theplanetary gear 106 and the station gear 109₃ is changed from the stateshown in FIG. 7 to that shown in FIG. 4 via the states shown in FIGS. 6and 10. In any case, FIGS. 5 and 6 show transitional states necessaryonly for the switchover, and the actual transmission of the drivingforce from the motor 102 to the driving force transmitting system is notperformed.

As described above, the ring gear 101b of the speed-reduction system 103is a rotatable gear disposed on the inner peripheral surface of thespool 101. Here, the spool 101 is in a floating state if this spool 101is not restricted in motion except when the driving force of the motor102 is transmitted to the spool gear 101a via the sun gear 105, theplanetary gear 106, and each of the station gears 109₁ -109₄. With sucha situation that the spool 101 is in a floating state, the spool 101 iscarelessly rotated when the film wound around the spool 101 is loosened,or when the planetary gears of the speed-reduction system 103 revolve orrotate on their respective axes. Therefore, in order to keep the spool101 from being in the floating state under the state that the drivingforce from the motor 102 is not transmitted to the spool; that is, theplanetary gear 106 engages the station gear 109₃ as shown in FIG. 6 or7, or under the state that the planetary gear 106 moves round the sungear 105 between the station gears 109 and 109₄ as shown in FIG. 8, 9 or10, the actuating mechanism is constructed in such a way that theinternal ring gear 101b acts as a fixed gear by stopping the rotation ofthe station gear 109₄. That is, only when the planetary gear 106 is inengagement with the station gear 109₁ or 109₄ (see FIGS. 3 through 5),the rotation of the spool 101 is permitted; and, the rotation of thespool 101 is prevented in other situations (see FIGS. 6 through 10) withthe provision of a spool locking mechanism which prevents the rotationof the station gear 109₄.

Referring to FIGS. 11 through 13, the spool locking mechanism comprisesthe carrier 107, a wedge-shaped cam surface 107a constituted of aninclined surface and a flat lower surface, and a spool locking lever 117to be pressed downward in engagement with the cam surface 107a and urgedby a spring (not shown) so that the spool locking lever 117 moves upwardin disengagement from the cam surface 107a. A rack portion 117a formedat an end of the spool locking lever 117 engages the station gear 109₄due to the upward movement of the spool locking lever 117, thuspreventing the rotation of the station gear 109₄. The spool lockinglever 117 is pivotally mounted on a shaft 117b, perpendicular to theshaft of the spool 101, located at the end thereof opposite the rackportion 117a. A pin 117c which moves on the cam surface 107a projectsfrom the center of the spool locking lever 117. A pair of cam surfaces107a are provided at locations on the carrier 107 so that the pin 117cfaces either of the cam surfaces 107a when the planetary gear 106engages the station gear 109₁ or 109₄. That is, when the planetary gear106 is in engagement with the station gear 109₁ or 109₄, the spoollocking lever 117 is pressed downward by the cam surface 107a, and hencethe rack portion 117a of the spool locking lever 117 does not engage thestation gear 109₄. When the planetary gear 106 is not in engagement withthe station gear 109₁ or 109₄, the spool locking lever 117 is notpressed downward by the cam surface 107a, and hence the rack portion117a of the spool locking lever 117 engages the station gear 109₄. As aresult of the engagement between the rack portion 117a and the stationgear 109₄, the rotation of the station gear 109₄, and thus the rotationof the spool 101, is prevented. In this manner, the spool 101 isprevented from being rotated by the speed-reduction system 103accommodated therein when the planetary gear 106 is revolving round thesun gear 105 or in engagement with the station gear 109₃. Although, inFIG. 10, the pin 117c looks like it is disposed on the flat cam surface107a, the pin 117c is actually in engagement with the inclined surfacethereof. With this state that the rack portion 117 partially engages thestation gear 109₄, the rotation of the station gear 109₄ is prevented.The rack portion 117a, the shaft 117b, the pin 117c and the cam surface107a are shown in only FIG. 1, not shown in FIGS. 3 through 10, forsimplicity.

Next, the construction of the switching mechanism installed in thedriving force transmitting system for switching the rotation of the samestation gear to two rotational directions, and its operation aredescribed below.

As regards the mechanism for preventing the planetary gear 106 fromrotating round the sun gear 105, the substantially circular carrier 107is rotatably installed on the output shaft 104 of the speed-reductionsystem 103 as shown in FIGS. 1 and 2. The planetary gear 106 isfrictionally installed on one side of the carrier 107 via the spring 108in between them. A pair of gear-tooth-shaped locking projections 110₁and 110₂ are formed on the carrier 107 at locations substantiallyopposite the planetary gear 106. A pair of locking levers 111₁ and 111₂each of which has a leading end portion able to engage the lockingprojection 110₁ and 110₂ and to disengage therefrom are formed atpositions facing the locking projections 110₁ and 110₂. The base portionof each locking levers 111₁, 111₂ is pivotally mounted on the camerabody, and the locking levers 111₁ and 111₂ are biased by a spring 112 atan intermediate portion therebetween in such a direction as the leadingend of each locking lever 111₁, 111₂ engages the locking projection110₁, 110₂. The locking lever 111₁ engages the locking projection 110₁or 110₂, thus preventing the carrier 107 from rotating counterclockwise,namely, the counterclockwise rotation of the planetary gear 106 roundthe sun gear 105. The locking lever 111₂ engages the locking projection110₁, 110₂, thus preventing the carrier 107 from rotating clockwise,namely, the clockwise rotation of the planetary gear 106 round the sungear 105. A cam 113 for allowing the engagement of the locking levers111₁, 111₂ with the locking projection 110₁, 110₂ and the disengagementthereof from the locking projection 110₁, 110₂ is frictionally installedon an end of the output shaft 104 of the speed-reduction system 103 viaa spring 114. The substantially circular cam 113 has a concave formed ata portion of the periphery thereof, thus forming a cam profile. The cam113 allows one of the locking levers 111₁, 111₂ to engage one of thelocking projections 110₁, 110₂ and allows the other of the lockinglevers 111₂, 111, to disengage from the same locking projections 110₂,110₁. Accordingly, when the carrier 107 rotates in one direction, it isprevented from rotating in the other direction by the cam 113. Each camfollower 111a, 111a which moves along the cam profile is integrated withthe locking lever 111₁, 111₂, respectively. The cam 113 rotates with theoutput shaft 104, and the amount of its rotation is limited to apredetermined range at which the planetary gear 106 is allowed or is notallowed to rotate round the sun gear 105. As shown in FIG. 1, the cam113 has a pair of attracted portions 113a and 113b projecting therefrom,while a magnet 115 having attracting portions at both ends is installedtherebetween. The rotatable angle of the cam 113 is limited to apredetermined degree so that when the cam 113 rotates in one direction,one of the projections 113a, 113b is brought into contact with one ofthe attracting portions of the magnet 115; and when the cam 113 rotatesin the opposite direction, the other of the projections 113b, 113a isbrought into contact with the other of the attracting portions of themagnetic 115. In other words, the magnet 115 acts as the stopper of thecam, thus limiting the rotatable range of the cam 113. The magnet 115 isswitched on when switching one station gear to another, the operation ofwhich is described later. Even though the motor 102 keeps rotating withthe attracted portion 113a, 113b bumping the attracting portion of themagnet 115, the cam 113 keeps stopping because the cam 113 keepsslipping against the output shaft 104 via the spring 114.

The sun gear 105 is installed on the output shaft 104 of thespeed-reduction system 103 with a "play" provided. More specifically, asshown in FIG. 14, a pair of projections 104a, 104a formed on the outputshaft 104 projects radially outwardly in opposite directions from theoutput shaft 104. A pair of concaves 105a, 105a for receiving theprojections 104a, 104a is formed on the inner peripheral surface of thebearing portion of the sun gear 105. The projections 104a, 104a areslidable circumferentially with respect to the inner surface of theconcaves 105a, 105 in a predetermined angular range. Accordingly, eventhough the output shaft 104 rotates, the rotation of the output shaft104 is not transmitted to the sun gear 105 until the projections 104a,104a are brought into contact with the inner wall of the concave 105a,105a. The slidable range of the projections 104a, 104a corresponds tothe range of the "play". That is, when the rotational direction of themotor 102 is switched reverse, the sun gear 105 starts rotating behindtime corresponding to the "play".

The operation due to the abovementioned construction is described below.That is, when the rotational direction of the motor 102 is switchedreverse in order to reverse the rotational direction of the planetarygear 106 at the same station, the cam 113 starts to rotate instantlytogether with the output shaft 104 in the same direction. The sun gear105, however, rests for the predetermined period of time correspondingto the "play", and when the "play" is up, the sun gear 105 startsrotating. In other words, when the motor 102 starts rotating reversely,the sun gear 105 is momentarily stopped. And, during the time when thesun gear 105 stops, only the cam 113 rotates to drive the locking levers111₁, 111₂. The time lag due to the "play" is so slight that a user cannot notice. Owing to the "play", the switching of the locking levers111₁, 111₂ is carried out reliably. The switching of the rotationaldirection of the motor 102 is described below with reference to FIGS. 3and 5. In the state shown in FIG. 5, the sun gear 105 is rotatingcounterclockwise, and the planetary gear 106 is rotating clockwise onits axis in engagement with the station gear 109₁. The force forrotating the planetary gear 106 round the sun gear 105 is checked by thelocking lever 111₁. At this time, the film is being rewound. When therotational direction of the motor 102 is reversed, the sun gear 105rests for the predetermined period of time during which the cam 113rotates clockwise, thus allowing the projection 113a to contact themagnet 115 as shown in FIG. 3 and stopping the rotation of the cam 113.As a result of the rotation of the cam 113, the locking lever 111₁disengages from the locking projection 110₂, whereas the locking lever111₂ engages the locking projection 110₂ as shown in FIG. 3. During thetime of switching the locking levers 111₁, 111₂, the sun gear 105 rests.Consequently, the planetary gear 106 and the carrier 107 also rest. As aresult of further rotation of the motor 102, the sun gear 105 starts torotate clockwise after the predetermined period of time, correspondingto the "play" passing. The carrier 107 is prevented from rotatingclockwise because the locking lever 111₂ is in engagement with thelocking projection 110₂. Thus, the planetary gear 106 remains at thesame position shown in FIG. 5, and it rotates on its axiscounterclockwise, accepting the rotation of the motor 102. At this time,the film is wound at a normal speed (see FIG. 3).

As described above, the sun gear 105 is connected to the output shaft104 with the "play" provided. Therefore, when the rotational directionof the planetary gear 106 is reversed with respect to the same stationgear, the cam 113 starts to rotate before the sun gear 105 does.Consequently, switching the locking levers 111₁, 111₂ is performedbefore the carrier 107 starts to rotate. The operation of reversing therotational direction of the planetary gear 106 relative to the samestation gear can be easily done by reversing the rotational direction ofthe motor 102.

The operation of the abovementioned switching mechanism for switchingthe station gears is described below.

The magnet 115 functions as a stopper to the cam 113 when the rotationaldirection of the carrier 107 is reversed. When switching from onestation gear to another, the magnet 115 is energized to attract theprojection 113a or 113b of the cam 113 thereto and to prevent therotation of the cam 113. As a result, the locking levers 111₁, 111₂ donot change their positions with respect to the cam 113. Accordingly,when the rotational direction of the motor 102 is reversed in thisstate, the carrier 107 is permitted to rotate in the direction that thelocking projection 110 parts from the locking lever 111₁, or 111₂ havingstopped the orbital movement of the locking projection 110. Inaccordance with this motion of the carrier 107, the planetary gear 106moves from one station gear to another. When the rotational direction ofthe motor 102 is reversed, the planetary gear 106 starts to rotate roundthe sun gear 105 behind time corresponding to the "play".

The magnet 115 is deenergized in correspondence with the timing when theplanetary gear 106 arrives at the position corresponding to any desiredstation gear. As a result, the cam 113 starts to rotate, switching thelocking levers 111₁, 111₂ is performed, and the carrier 107 is locked bythe locking lever 111₁ or 111₂ so that the planetary gear 106 is stoppedat a desired station gear. A code indicating the rotational position ofthe carrier 107 is provided thereon. A photoreflector 116 is positionedto face the code so as to read it. This positional detection mechanismcomprising the code and the photoreflector 116 allows the location ofthe planetary gear 106 to be always monitored.

For example, in case that the planetary gear 106 changes its positionfrom the state, in which the film is being rewound, shown in FIG. 5 tothe state, in which the driving force from the motor 102 is transmittedto the station gear 109₃, shown in FIG. 7 via the state shown in FIG. 8,the magnet 115 is energized, thus attracting the projection 113bthereto. Accordingly, the locking levers 111₁ and 111₂ keep their stateshown in FIG. 5. When the rotational direction of the motor 102 isreversed with the positional state shown in FIG. 5 being kept, the sungear 105 starts to rotate clockwise behind time corresponding to the"play", and the planetary gear 106 starts rotating round the sun gear105 in the direction that the planetary gear 106 disengages and partsfrom the station gears 109₁ and 109₂ (see FIG. 8). When the magnet 115is deenergized just before the arrival of the planetary gear 106 at aposition corresponding to the station gear 109₃, the cam 113 is free tomove. As a result, the rotation of the output shaft 104 is transmittedto the cam 113 via the friction spring 114, and the attracted portion113b of the cam 113 starts parting from the magnet 115, as shown inFIGS. 8 and 7. In accordance with the rotation of the carrier 107, thelocking projection 110₁ formed on the carrier 107 moves in between thelocking lever 111₁ and 111₂, the locking lever 111₁ is pressed radiallyoutwardly by the cam 113, and the locking projection 110 is stopped bythe locking lever 111₂ with the locking lever 111₂ being moved radiallyinwardly as shown in FIG. 7. This position corresponds to the positionwhere the planetary gear 106 engages the station gear 109₃ and thedriving force from the motor 102 is transmitted thereto. As describedpreviously, the spool locking lever 117 keeps preventing the rotation ofthe station gear 109₄, and therefore the rotation of the spool 101,after the planetary gear 106 parts from the station gears 109₁ and 109₂.

As described above, according to the first embodiment of the presentinvention, the planetary gear 106 can be rotated round the sun gear 105in both clockwise and counterclockwise direction to switch the drivingforce transmitting system, and the planetary gear 106 can also berotated on its axis in both direction so that the rotations in bothdirections from the motor 102 can be transmitted to any one of thestation gears 109₁ -109₄. In particular, the magnet can be constructedsmaller than conventional plungers and constructed more inexpensively. Asmall force suffices for disengaging the locking lever from the lockingprojection, because the locking projection to disengage never fails topart from the locking lever, thus making the force to drive the camconsiderably smaller. That is, a greater force is not required toovercome the frictional force exerting between the locking lever and thelocking portion according to the conventional art. By using the magnets,it is possible to make the actuating mechanism smaller and compact.

In this first embodiment, the photoreflector 116 is located at aposition facing the carrier 107, but in order to accomplish moreaccurate control, it is effective to dispose a means such as aphotoreflector or a photointerrupter for detecting the rotational amountof the motor 102 between the output shaft of the motor 102 and theoutput shaft 104 of the speed-reduction system 103.

Providing a means for detecting the rotational position of the cam 113makes it possible to carry out the following control. That is, forexample, in case that the planetary gear 106 changes its position fromone state that the planetary gear 106 engages one station gear 109₃ toanother state that the planetary gear 106 engages another station gear,the planetary gear 106 has two directions to rotate around the sun gear105. Here, one of the attracted portions 113a, 113b of the cam 113contacts the magnet 115 in accordance with a rotational direction of themotor 102; therefore, the planetary gear 106 can be allowed to rotateonly in one direction in order to switch from one station gear toanother with the attracted portion of the cam 113 being attracted to themagnet 115.

On the other hand, if one wants to reverse the rotational direction ofthe planetary gear 106 around the sun gear 105, switching from onestation gear to another can be performed after reversing the controldirection by the locking levers 111₁ and 111₂. In this case, if therotational direction of the motor 102 is reversed a bit, and if therotated amount thereof is detected from the position of the cam 113, itis possible to freely select the attracted portion 113a, 113b to beattracted by the magnet 115. In this construction, it is free to choosethe direction of rotation of the planetary gear around the sun gear inorder to switch from one station gear to another.

In the first embodiment, the projections 113a and 113b are formedparallel with respect to each end surface of the magnet 115 at theposition where the projection 113a or 113b contacts the magnet 115. Ifthe attracted portions 113a, 113b of the cam 113 are constructed asseparate members free to move to some extent, each attracted portion113a, 113b can be attracted to the magnet 115 in closer contacttherebetween.

An actuating mechanism according to a second embodiment is describedbelow with reference to FIGS. 15 through 25. Similarly to the firstembodiment, stations can be switched from one to the other and therotational direction of a planetary gear can be reversed with themechanism comprising the output shaft of a reduction system connected toa sun gear with a "play" provided therebetween, a carrier having lockingprojections, locking levers driven by a cam and preventing the rotationof the carrier, namely, the rotation of the planetary gear around thesun gear, and a magnet serving as the stopper of the cam and performingattracting operation. Here, the mechanisms of the second embodimenthaving the same construction and operation as those of the firstembodiment are not described. Unlike the first embodiment in which themagnet 115 having attracting portions at both ends thereof is used toallow the planetary gear 106 to rotate round the sun gear 105 clockwiseand counterclockwise in switching the stations from one to the other, amagnet 215 according to the second embodiment has an attracting portionat one end thereof. Accordingly, the position of a projection 213a of acam 213 is determined by being attracted to the magnet 215 in switchingstations from one to the other. That is, the postures of locking levers211₁ and 211₂ are kept constant when the projection 213a is attracted tothe magnet 215, and thus the carrier 207 is rotatable in only onedirection. Accordingly, the planetary gear 206 is allowed to rotate onlyclockwise in switching the stations from one to the other as shown inFIG. 15. The cam 213 is allowed to rotate in the range in which theprojection 213a is rotatable between the magnet 215 and a stopper pin230. The locking lever 211₂ is pivoted by the cam 213, whereas thelocking lever 211₁ functions as a ratchet claw permitting the carrier207 to rotate clockwise and preventing the carrier 207 from rotatingcounterclockwise. The locking lever 211₁ acts an actuator for turning ona switch 231 each time the locking lever 211₁ is pressed radiallyoutwardly by a locking projection 210₁₋₃ of the carrier 207. The switch231 outputs signals each time the switch 231 is turned on, thus countingthe number of stations through which the planetary gear 206 has passed.

A station gear 209₁ is an input gear for transmitting the driving forcefrom a motor 202 to a system for driving a photographic lens barrel 222in zooming operation. A station gear 209₂ is an input gear fortransmitting the driving force from a motor 202 to a film-rewindingsystem. A station gear 209₃ is an input gear for transmitting thedriving force from a motor 202 to a film-winding system.

In the second embodiment, as shown in FIG. 32, a spool gear 201a isformed on the peripheral surface of the upper end of the spool 201. Aspool-driving gear 235 engages a gear 234 formed on the upper end of ashaft 233 extending vertically upward from the station gear 209₃ andhaving a configuration similar to the station gear 209₃. Thespool-driving gear 235 engages the spool gear 201a. In winding the film,the state of the actuating mechanism is as shown in FIG. 17. Referringto FIG. 17, the sun gear 205 rotates counterclockwise while theplanetary gear 206 does not rotate round the sun gear 205 but rotates onits axis in engagement with the station gear 209₃, thus transmitting thedriving force from the motor 202 to the station gear 209₃ because therotation of the carrier 207 is prevented by the locking lever 211₁. Thelens barrel 222 is driven by a worm gear 223 provided on the shaft 233.As shown in FIG. 36, a gear train of the film-rewinding system extendsfrom the station gear 209₂ along the bottom surface of the camera body.Referring to FIG. 36, reference numeral 240 shows a film cartridge and241 shows a gear, connected with a fork (not shown), for driving thespool of the film cartridge 240.

A peripheral ring gear 232 of a speed-reduction system 203 comprising agear train is a fixed ring gear formed at an end of the camera body. Asshown in FIG. 16, the diameter of the fixed ring gear 232 is a littlebit smaller than the outer diameter of the spool 201. Accordingly, thefilm wound round the spool 201 extends downward from the lower end ofthe spool 201. This construction reduces the length of thespeed-reduction system 203, projecting downward from the spool chamber,thus allowing the camera body to be compact.

The operation of reversing the driving rotational direction of theplanetary gear 206 at the same station is performed similarly to thefirst embodiment.

In switching film-winding operation to zooming operation, the rotationaldirection of the motor 202 is reversed and the magnet 215 is energizedas shown in FIG. 17 so that the magnet 215 attracts the projection 213aof the cam 213 thereto. As a result, as shown in FIG. 18, the lockinglevers 211₁ and 211₂ allow the carrier 207 to rotate clockwise. That is,the planetary gear 206 disengages from the station gear 209₃ and rotatescounterclockwise round the sun gear 205, thus approaching to a positionimmediately before the station gear 209₁. At this time, the lockingprojection 210₃ pushes the locking lever 211₁ radially outwardly and theswitch 231 is turned on, thus outputting a signal and the magnetdeenergized. Consequently, the projection 213a is released from themagnet 215, the cam 213 rotates together with the carrier 207, and theprojection 213a is moved into contact with the stopper pin 230 with thelocking lever 211₂ engaging the locking projection 210₃. As a result,the rotation of the carrier 207 is stopped and the rotation of theplanetary gear 206 around the sun gear 205 is stopped (see FIG. 19).When the motor 202 keeps rotating with the sun gear 205 rotatingclockwise, the planetary gear 206 (see FIG. 19) rotates counterclockwiseon its axis, thus transmitting the driving force from the motor 202 tothe station gear 209₁. At this time, the zooming operation is switchedfrom the telescopic side to the wide side. When the rotational directionof the motor 202 is reversed, the cam 213 rotates counterclockwise whilethe sun gear 205 and the planetary gear 206 rest for a predeterminedperiod of time corresponding to the "play", thus moving the projection213a into contact with the magnet 215 (see FIG. 20). At this time, thelocking lever 211₂ disengages from the projection 210₃ while the lockinglever 211₁ prevents the carrier 207 from rotating counterclockwise.Therefore, the planetary gear 206 starts to rotate clockwise on itsaxis, thus transmitting the driving force from the motor 202 to thestation gear 209₁. At this time, the zooming operation is switched fromthe wide side to the telescopic side. Similarly to the first embodiment,backlash is removed in the zooming operation in the second embodiment.When the zooming operation is completed, the actuating mechanism is setin the state, as shown in FIG. 20, for preparing the switch-over to thestation gear 209₃.

FIG. 19 or 20 shows the state immediately before the zooming operationis switched to the film-winding operation. When the state of the zoomingoperation is as shown in FIG. 19, the rotational direction of the motor202 is reversed to obtain the state shown in FIG. 20 before theswitching operation is started. When the magnet 215 is energized withthe state shown in FIG. 20, the projection 213a is attracted to themagnet 215 and hence, the cam 213 is held at the position shown in FIG.20. When the rotational direction of the motor 202 is switched from thecounterclockwise direction to the clockwise direction, the carrier 207starts to rotate and thus the planetary gear 206 starts to rotateclockwise round the sun gear 205 (see FIG. 18). When the planetary gear206 continues to rotate clockwise round the sun gear 205, the lockinglever 211₁ passes over the locking projections 210₂ and 210₁sequentially (from state shown in FIG. 20 to state shown in FIG. 24 viastate shown in FIGS. 23 and 22). During this period of time, the switch231 is turned on twice. When the switch 231 outputs a second signal, themagnet 215 is deenergized. As a result, the projection 213a is releasedfrom the magnet 215 and thus the cam 213 rotates together with thecarrier 207, and the projection 213a is brought into contact with thestopper pin 230. Consequently, the locking lever 211₂ engages thelocking projection 210₁. Thereafter, the carrier 207 stops rotation, andthus the planetary gear 206 stops rotating round the sun gear 205, thusengaging the station gear 209₃. When the rotational direction of themotor 202 is reversed, the cam 213 rotates counterclockwise while thesun gear 205 and the planetary gear 206 rest for the period of timecorresponding to the "play", and the projection 213a is brought intocontact with the magnet 215. When the motor 202 continues to rotatefurther, the film-winding operation is performed in the state shown inFIG. 17.

When the roll of film is completely taken up around the spool 201, thefilm is forcibly stopped. Then, the state of the actuating mechanismshown in FIG. 17 changes to the state thereof shown in FIG. 21 via thestates shown in FIGS. 18 and 23. When the planetary gear 206 approachesto a position immediately before the station gear 209₁, the lockingprojection 210₃ presses the locking lever 211₁ radially outwardly, thusturning on the switch 231. When the planetary gear 206 approaches to aposition immediately before the station gear 209₂, the switch 231 isturned on again, thus outputting a second signal due to the operation ofthe locking projection 210₂ as shown in FIG. 23. When the switch 231outputs the second signal, the magnet 215 is deenergized. As a result,the projection 213a is released from the magnet 215 and thus the cam 213rotates together with the carrier 207, and the projection 213a isbrought into contact with the stopper pin 230. Consequently, the lockinglever 211₂ engages the locking projection 210₁. Thereafter, the carrier207 stops rotation, and the planetary gear 206 stops rotating round thesun gear 205 (see FIG. 21). When the motor 202 continues to rotatefurther with the sun gear 205 rotating clockwise, the planetary gear 206rotates counterclockwise on its axis with the state shown in FIG. 21maintained, thus transmitting the driving force of the motor 202 to thestation gear 209₂. At this time, the film is rewound.

FIGS. 22 through 25 show a transitional state of the actuating mechanismat each time when the station gear is switched from one to the other.FIG. 22 shows a switch-over preparation state with the magnet 215energized through which the state of the actuating mechanism shown inFIG. 21 is switched to the state thereof shown in FIG. 17 or FIG. 19.FIG. 23 shows a state of the actuating mechanism in which when theplanetary gear 206 passes the station gear 209₁, the switch 231 isturned on due to the operation of the locking lever 211₁. FIG. 24 showsa state thereof in which when the planetary gear 206 passes the stationgear 209₂, the switch 231 is turned on due to the operation of thelocking lever 211₁. FIG. 25 shows another state thereof subsequent tothe state shown in FIG. 17.

Similarly to the first embodiment, in the second embodiment, it ispossible to provide a position-detecting mechanism for detecting therotational position of the carrier 207 or a detecting mechanism fordetecting the rotational amount of the motor 202. It is possible toprovide a means for detecting the rotational position of the cam 213 soas to control the timing when the projection 213a is attracted to themagnet 215 in switching the station gear from one to the other. It isalso possible to provide a pivotal member on the projection 213a of thecam 213 so that the projection 213a can be reliably attracted to themagnet 215.

An actuating mechanism according to a third embodiment is describedbelow with reference to FIGS. 26-30 and FIG. 33. Similarly to the secondembodiment, the actuating mechanism comprises a planetary carrier havinglocking projections, a first locking lever driven by a cam andpreventing one directional rotation of the planetary carrier, viz. therotation of the planetary gear around the sun gear, a second lockinglever acting as a ratchet claw for the carrier, a stopper pin forlimiting the rotational amount of the cam, and a magnet, in whichconstruction the station gears are changed and the rotational directionof a selected station gear can be reversed. The magnet attracts the camthereto, thus holding it temporarily. Accordingly, the mechanism of thethird embodiment having the same construction and operation as those ofthe second embodiment are not described below. Unlike the first andsecond embodiments in which the output shaft of the speed reductionsystem and the sun gear are connected with each other with a "play"provided to make the cam plate rotate before the sun gear rotates inreversing the rotational direction of the motor, according to the thirdembodiment, a differential mechanism is provided therein. Referring toFIGS. 26 and 27, a cylindrical peripheral ring gear 350 of a speedreduction system 303 is rotatable. An extended portion 350a extendingradially outwardly from the lower end of the peripheral ring gear 350 isformed and a cam surface 350b is integrally formed on the side of theextended portion 350a. In this manner, an integrated construction hasthe driving cam of a locking lever 311₁ and the ring gear 350 integralwith the driving cam. This construction includes a projection 350c, tobe attracted to the magnet 315, extending outward from the extendedportion 350a. The rotatable amount of the ring gear 350 is limited to acertain range, and the projection 350c is pivotal between the magnet 315and a stopper pin 330. A pivotal contact piece 352 is formed on an endof the projection 350c by fixing a shaft thereof to the piece 352 sothat the projection 350c can be appropriately attracted to the magnet315. The ring gear 350 is connected with the camera body with a bayonetso that the ring gear 350 is not disconnected from the camera body inthe axial direction thereof (axial direction of spool 301) and allowedto rotate within a predetermined angular range. One end of a helicalspring 351 is locked on a boss of the camera body and the other endthereof is locked on the ring gear 350. The helical spring 351 biasesthe projection 350c so that the ring gear 350 rotates clockwise in FIG.26. That is, the helical spring 351 biases the ring gear 350 in thedirection in which the projection 350c is pressed against the stopperpin 330. A friction spring 353 for rotating a planetary gear 306 round asun gear 305 is interposed between a carrier 303c of a planetary geartrain of the speed reduction system 303 and a planetary carrier 307 of aswitching system. The locking lever 311₁ is driven by the cam surface350b and another locking lever 311₂ acts as a ratchet claw permittingthe carrier 307 to rotate only counterclockwise. Unlike the first andsecond embodiments, the locking levers 311₁, 311₂ engage a lockingprojection. As shown in FIG. 26, in the state in which the locking lever311₁ is in engagement with a locking projection 310₁, a slight gap isprovided between the locking lever 311₂ and a locking projection 310₃.The gap is as small as approximately 4° and allows the locking lever311₁ to disengage from the locking projection 310₁ easily. That is, thecarrier 307 rotates clockwise by the length of the gap before thelocking lever 311₁ is disengaged from the locking projection 310₁. As aresult, a slight gap is provided between the locking lever 311₁ and thelocking projection 310₁, thus allowing the locking lever 311₁ todisengage easily from the locking projection 310₁.

Next, the differential mechanism comprising the planetary speedreduction system 303 is described below with reference to FIG. 33. InFIG. 33, of two stages of the planetary gear train, only the planetarygear train of the second stage with respect to the motor is shown. Butthe planetary gear train of the first stage has the same operation asthat of the second stage. In the planetary speed reduction system 303,both the carrier 303c of the reduction system and the ring gear 350 arerotatable. When the motor 302 rotates, either carrier 303c of thereduction system or the ring gear 350 rotates according to the magnitudeof loads applied thereto with the motor 302 rotating. That is, if theload of the former is greater than the latter, the former rests and thelatter rotates, and vice versa. At this time, the rotational force ofthe motor 302 is transmitted to the carrier 303c in the same rotationaldirection as that of the motor 302, whereas the rotational force of themotor 302 is transmitted to the ring gear 350 in the rotationaldirection opposite to that of the motor 302. Accordingly, if the ringgear 350 is fixed when the motor 302 rotates, i.e., when the projection350c is pressed against the stopper pin 330 or the magnet 315 orattracted to the magnet 315, the carrier 303c of the reduction system303 rotates round a sun gear 303s of the reduction system together witha planetary gear 303p of the planetary gear train of the reductionsystem 303. The carrier 303c of the reduction system 303 is coaxiallyconnected with the sun gear 305, with a "play" provided. The carrier303c of the reduction system 303 is an output shaft of the reductionsystem 303. When the carrier 303c of the reduction system 303 rotates asdescribed above, the driving force from the motor 302 is transmitted tothe planetary gear 306 via the carrier 307 or the sun gear 305. As aresult, the planetary gear 306 rotates round the sun gear 305 or rotateson its axis, thus switching stations or transmitting the driving forcefrom the motor 302 to a desired station gear.

When the load of the carrier 303c of the reduction system 303 is greaterthan that of the ring gear 350, the planetary gear 303p of the reductionsystem 303 rotates on its axis in the direction opposite to therotational direction of the motor 302, thus rotating the ring gear 350in the direction opposite to the rotational direction of the motor 302.Referring to FIG. 26 or 28, the operation of reversing the rotationaldirection of the station gear 309 is described below, supposing that thestation gear 309₃ is driven. When the motor 302 rotates counterclockwisewith the state of the actuating mechanism shown in FIG. 26, the sun gear305 rotates counterclockwise and the locking lever 311₁ prevents thecarrier 307 from rotating counterclockwise. When the planetary gear 306rotates clockwise on its axis, the station gear 309₃ rotatescounterclockwise. The state in which any one of the station gears 309 isrotated counterclockwise due to the counterclockwise rotation of themotor 302 is referred to as forward drive state. When the motor 302rotates clockwise in the state shown in FIG. 28, the sun gear 305 alsorotates clockwise, and the locking lever 311₂ prevents the carrier 307from rotating clockwise. When the planetary gear rotatescounterclockwise on its axis, the station gear 309₃ rotates clockwise.The state in which any one of the station gear 309 is rotated clockwisedue to the clockwise rotation of the motor 302 is referred to asbackward drive state. To switch the station gear 309 from the forwarddrive state to the backward drive state, first, the rotational directionof the motor 302 is reversed from the forward drive state to thebackward drive state. As a result, the clockwise rotational force of themotor 302 acts on the carrier 307 due to the frictional force of thefriction spring 353. Immediately after the rotational direction of themotor 302 is reversed, the locking projection 310₃ is brought intocontact with the locking lever 311₂, and the carrier 307 is preventedfrom rotating clockwise. The actuating mechanism has the followingoperation due to the above-described loads applied to the carrier 303cof the speed reduction system 303 and the ring gear 350: the loadexerted on the ring gear 350 with respect to the driving force of themotor 302 is the biasing force of the helical spring 351, and the loadapplied to the carrier 303c of the reduction system 303 is thefrictional force of the friction spring 353 interposed between thecarrier 303c of the reduction system 303 and the carrier 307 of theswitching system. At this time, the rotation of the carrier 307 isprevented by the locking lever 311₂. The biasing force of the helicalspring 351 is set to be smaller than the frictional force of thefriction spring 353. Accordingly, when the rotational direction of themotor 302 is reversed as described above, the driving force of the motor302 rotates the ring gear 350 counterclockwise against the urging forceof the helical spring 351 until the projection 350c is brought intocontact with the magnet 315. Until the projection 350c is brought intocontact with the magnet 315, the carrier 303c of the reduction system303, the sun gear 305, and the planetary gear 306 rest. The state thatthe sun gear 305 and the planetary gear 306 rest with the motor 302rotating clockwise and the projection 350c in contact with the magnet315 is referred to as ring gear charge state. The ring gear charge stateis also the state in which the preparation for switching the station hasbeen completed, which will be described later. When the motor 302continues to rotate in the ring gear charge state, and, when the sungear 305 does not have the "play" any more, the corresponding stationgear (station gear 309₃ in FIG. 28) starts rotating clockwise, with thesun gear 305 rotating clockwise together with the motor 302, the lockinglever 311₂ preventing the carrier 307 from rotating clockwise, and theplanetary gear 306 rotating counterclockwise. That is, the station gear309₃ is in the backward drive state.

Description is made on the above-described loads applied to the carrier303c of the reduction system 303 and the ring gear 350 at the time whenthe rotational direction of the motor 302 is switched to thecounterclockwise direction so as to switch the backward drive state tothe forward drive state. When the motor 302 is rotated counterclockwise,the clockwise driving force acts on the ring gear 350. The biasing forceof the helical spring 351 is applied clockwise to the ring gear 350.That is, a negative load is applied to the ring gear 350 because themotor 302 is rotated counterclockwise. The driving force is appliedcounterclockwise to the carrier 303c of the reduction system 303. Inthis state, the planetary carrier 307 is not prevented fromcounterclockwise rotation round the sun gear 305; therefore, the carrier303c of the speed reduction system 303 allows the carrier 307 to rotatewith no load applied to the carrier 303c in rotating the planetary gear306 round the sun gear 305 by means of the frictional force of thefriction spring 353. That is, the driving force of the motor 302 rotatesthe ring gear 350 clockwise due to the balance between the negative loadand no-load until the projection 350c is brought into contact with thestopper pin 330. At this time, the locking lever 311₁ is driven by thecam surface 350b formed on the ring gear 350, thus taking a position atwhich the carrier 307 is prevented from rotating counterclockwise. Thecarrier 303c of the speed reduction system 303, the carrier 307, the sungear 305, and the planetary gear 306 rest during the period of timebetween the time at which the motor 302 has reversed its rotationaldirection and the time at which the projection 350c contacts the stopperpin 330. When the motor 302 keeps rotating and the sun gear 305 has no"play", the sun gear 305 rotates counterclockwise together with themotor 302. At this moment, the locking lever 311₁ prevents the carrier307 from rotating counterclockwise, the planetary gear 306 startsrotating clockwise, and the corresponding station gear (station gear309₃ in FIG. 26) is rotated counterclockwise. That is, the station gear309₃ is set to the forward drive state.

The operation of switching the station is described below. In the thirdembodiment, the switch-over of the station starts from the ring gearcharge state. Thus, in case of trying to switch the station with theforward drive state, the forward drive state is once shifted to the ringgear charge state as described above. The magnet 315 is energized in thering gear charge state so that the projection 350c, namely, the ringgear 350 is attracted thereto. The motor 302 is rotated counterclockwiseto rotate the carrier 303c of the speed reduction system 303counterclockwise. At this time, the locking lever 311₁ allows thecarrier 307 to rotate counterclockwise. Because the carrier 303c of thereduction system 303 and the carrier 307 are connected with each otherby the friction spring 353, the carrier 307 rotates counterclockwise,and thus the planetary gear 306 is switched to another station gear 309.At this time, the locking lever 311₂ is pushed outward by the lockingprojection 310. The locking lever 311₂ is biased toward the carrier 307by a spring 354 serving as a switch contact strip and outputting anON-signal in contact with a switch pin 355 each time the locking lever311₂ is pushed by the locking projection 310. Similarly to the secondembodiment, the number of the station gears 309 which the planetary gear306 passes is counted by counting the number of the ON-signals. When themagnet 315 is deenergized as the planetary gear 306 approaches to aposition immediately before a predetermined station gear 309, the ringgear 350 is released from the magnet 315. The ring gear 350 rotatesclockwise due to the biasing force of the helical spring 351 and therotation of the motor 302, and the cam surface 350b of the ring gear 350locks the locking lever 311₁. Accordingly, the carrier 307 is preventedfrom rotating counterclockwise, and the planetary gear 306 engages thepredetermined station gear 309 (see FIG. 30). At this time, there is the"play" left between the sun gear 305 and the carrier 303c of the speedreduction system 303, and the sun gear 305 does not start to rotate.When the motor 302 continues to rotate counterclockwise, the actuatingmechanism operates with the forward drive state after the "play" isremoved, whereas when the rotational direction of the motor 302 isreversed, the actuating mechanism operates with the backward drive stateafter passing the ring gear charge state. That is, in the stateimmediately after the station is switched, both the sun gear 305 and theplanetary gear 306 rest even though the motor 302 rotates a bitexcessively, thus avoiding any unexpected driving state, no matterwhether it is in the forward drive state or in the backward drive state.The "play" also overcomes a possibility that an unexpected station gear(station gear 309₂ in the above example) is driven while the planetarygear 306 is moving toward one desired station gear. Furthermore, the"play" avoids a possibility of getting the backward drive state due toan overrun of the motor 302 in case that it is once set in the ring gearcharge state in order to switch the station with the forward drive statekept. The function of the "play" for preventing the station from beingdriven unexpectedly in reversing the control cam (cam surface 350b) forswitching the station holds true for the first and second embodiments.

The film-rewinding mechanism according to the third embodiment, which isnot described above, can be constructed similarly to the secondembodiment, for example, by extending the gear train of thefilm-rewinding mechanism from the station gear 309₂ along the bottomsurface of the camera body.

In each embodiment described above, the station gears can be rotated intwo rotational directions. If it is desired that each station gear isrotated only in one rotational direction, the actuating mechanism can bemade simple in construction. That is, the actuating mechanism can beconstructed such that one locking lever 411 provided therein acts as aratchet claw allowing the planetary carrier 407 to rotate only in onerotational direction as shown in FIG. 31. In an example shown in FIG.31, even if the sun gear 405 rotates clockwise, the rotation of theplanetary carrier 407 is prevented by the locking lever 411. Therefore,a planetary gear 406 rotates on its axis counterclockwise, thus rotatingthe station gears 409 clockwise. On the other hand, when the sun gear405 rotates counterclockwise, the planetary carrier 407 is able torotate, pushing the locking lever 411 radially outwardly. As a result,the planetary gear 406 rotates counterclockwise round the sun gear 405.The planetary gear 406 can be switched to a desired station gear 409based on the number of ON-signals outputted from a switch 431. It ispossible to use a photoreflector or a photointerrupter, instead of theswitch 431, similar to those used in the first embodiment.

Station gears 409₁ and 409₂ sandwiching two idle gears in between themare rotated in opposite rotational directions by a common drivingsystem, and they allow zooming operation to be performed from thetelescopic side to the wide side or vice versa. It is also possible toadopt a one-direction clutch mechanism having a known constructioninstead of a ratchet mechanism having a locking lever 411.

Although the present invention has been fully described in connectionwith the preferred embodiments thereof with reference to theaccompanying drawings, it is to be noted that various changes andmodifications are apparent to those skilled in the art. Such changes andmodifications are to be understood as included within the scope of thepresent invention as defined by the appended claims unless they departtherefrom.

What is claimed is:
 1. An actuating mechanism comprising:a drivingsource with a driving shaft able to rotate in both rotationaldirections; a sun gear driven by the driving shaft; a planetary carriermounted rotatably with respect to the sun gear; a planetary gear,engaging with the sun gear, which is frictionally mounted on theplanetary carrier, such that friction is generated between the planetarygear and the planetary carrier, so as to revolve around the sun gear; atleast one transmission gear, located along an orbital path of theplanetary gear, which can engage with the planetary gear; and a controlmechanism which switches between a first state in which the planetarygear is allowed to revolve along the orbital path, and a second state inwhich the planetary gear is allowed to rotate on its axis but notallowed to revolve along the orbital path, wherein the control mechanismis driven by the driving shaft of the driving source.
 2. An actuatingmechanism as claimed in claim 1, wherein the control mechanism includesmeans for prohibiting the planetary gear from revolving along theorbital path in both directions.
 3. An actuating mechanism as claimed inclaim 1, wherein the at least one transmission gear can be driven torotate in both rotational directions.
 4. An actuating mechanismcomprising:a driving source with a driving shaft able to rotate in bothrotational directions; a sun gear driven by the driving shaft; aplanetary carrier mounted rotatably with respect to the sun gear; aplanetary gear, engaging with the sun gear, which is frictionallymounted on the planetary carrier so as to revolve around the sun gear;at least one transmission gear, located along an orbital path of theplanetary gear, which can engage with the planetary gear; a controlmechanism which switches between a first state in which the planetarygear is allowed to revolve along the orbital path, and a second state inwhich the planetary gear is allowed to rotate on its axis but notallowed to revolve along the orbital path, wherein the control mechanismis driven by the driving shaft of the driving source; a magnet forcontrolling the control mechanism so that the control mechanism is keptin the first state; wherein the control mechanism has a part which ismagnetically pulled by the magnet; and the control mechanism is socontrolled that the control mechanism is kept in the first state withthe part of the control mechanism being magnetically pulled by themagnet.
 5. An actuating mechanism comprising:a driving source with adriving shaft able to rotate in both rotational directions; a sun geardriven by the driving shaft; a planetary gear, engaging with the sungear, which can revolve around the sun gear and rotate on its axis at adesired position along an orbital path taken around the sun gear; atleast one transmission gear, located along the orbital path of theplanetary gear, which can engage with the planetary gear; a firstcontrol mechanism which switches between a first state in which theplanetary gear is allowed to revolve along the orbital path, and asecond state in which the planetary gear is allowed to rotate on itsaxis but not allowed to revolve along the orbital path; and a secondcontrol mechanism for controlling the first control mechanism so thatthe first control mechanism is kept in the first state; wherein thefirst control mechanism is driven by the driving shaft of the drivingsource.
 6. An actuating mechanism as claimed in claim 5, wherein thefirst control mechanism includes means for prohibiting the planetarygear from revolving around the orbital path in both directions.
 7. Anactuating mechanism as claimed in claim 5, wherein at least onetransmission gear can be driven to rotate in both rotational directions.8. An actuating mechanism comprising:a driving source with a drivingshaft able to rotate in both rotational directions; a sun gear driven bythe driving shaft; a planetary gear, engaging with the sun gear, whichcan revolve around the sun gear and rotate on its axis at a desiredposition along an orbital path taken around the sun gear; at least onetransmission gear, located along the orbital path of the planetary gear,which can engage with the planetary gear; a first control mechanismwhich switches between a first state in which the planetary gear isallowed to revolve along the orbital path, and a second state in whichthe planetary gear is allowed to rotate on its axis but not allowed torevolve along the orbital path; a second control mechanism forcontrolling the first control mechanism so that the first controlmechanism is kept in the first state; wherein the second controlmechanism is a magnet; and the first control mechanism has a part whichis magnetically pulled by the magnet, and the first control mechanism isso controlled that the first control mechanism is kept in the firststate such that the planetary gear may revolve around the orbital pathonly when the part thereof is magnetically pulled by the magnet.
 9. Anactuating mechanism comprising:a motor with a driving shaft able torotate in both rotational directions; a sun gear driven by the drivingshaft; a planetary gear, engaging with the sun gear, which can revolvearound the sun gear and rotate on its axis at a desired position alongan orbital path taken around the sun gear; at least one transmissiongear, located along the orbital path of the planetary gear, which canengage with the planetary gear; a locking mechanism which prohibits theplanetary gear from revolving along the orbital path, wherein thelocking mechanism comprises a movable first locking member which canprohibit the planetary gear from revolving along the orbital path in oneorbital direction, the locking member further comprises a movable secondlocking member which is movable relative to the first locking member andwhich can prohibit the planetary gear from revolving along the orbitalpath in another orbital direction.
 10. An actuating mechanism as claimedin claim 9, wherein at least one of the first locking member and thesecond locking member has a locking state in which the planetary gear isprohibited from revolving along the orbital path, and an unlocking statein which the planetary gear is allowed to revolve along the orbitalpath.
 11. An actuating mechanism as claimed in claim 10, furthercomprising an actuator for keeping the locking member in the unlockingstate.
 12. An actuating member as claimed in claim 11, wherein theactuator is a magnet.
 13. An actuating mechanism as claimed in claim 11,wherein the locking member is switched between the locking state and theunlocking state by the actuator.
 14. An actuating mechanism as claimedin claim 9, wherein there are provided at least three transmissiongears.
 15. An actuating mechanism as claimed in claim 9, wherein arotational direction of the driving shaft of the motor during arevolution of the planetary gear around the sun gear is different from arotational direction of the driving shaft thereof before the revolutionof the planetary gear around the sun gear is started.
 16. An actuatingmechanism as claimed in claim 9, further comprising a planetary carrier,rotatably mounted with respect to the sun gear, on which the planetarygear is frictionally mounted so as to revolve around the sun gear. 17.An actuating mechanism comprising:a motor with a driving shaft able torotate in both rotational directions; a sun gear driven by the drivingshaft of the motor; a planetary gear, engaging with the sun gear, whichcan revolve around the sun gear and rotate on its axis at a desiredposition along an orbital path taken around the sun gear; at least onetransmission gear, located along the orbital path of the planetary gear,which can engage with the planetary gear; and a locking member which canprohibit the planetary gear from revolving along the orbital path,wherein the locking member comprises a first locking member which canprohibit the planetary gear from revolving along the orbital path in oneorbital direction, the locking member further comprises a second lockingmember which can prohibit the planetary gear from revolving along theorbital path in another orbital direction; wherein at least one of thefirst locking member and the second locking member is driven by themotor so that the locking member moves between a locking state in whichthe planetary gear is prohibited from revolving along the orbital pathand an unlocking state in which the planetary gear is allowed to revolvealong the orbital path.
 18. An actuating mechanism as claimed in claim17, further comprising an actuator for keeping the locking member in theunlocking state.
 19. An actuating mechanism as claimed in claim 18,wherein the actuator is a magnet.
 20. An actuating mechanism as claimedin claim 17, wherein there are provided at least three transmissiongears.
 21. An actuating mechanism as claimed in claim 17, wherein arotational direction of the driving shaft of the motor during arevolution of the planetary gear around the sun gear is different from arotational direction of the driving shaft thereof before the revolutionof the planetary gear around the sun gear is started.
 22. An actuatingmechanism, comprising:a motor with a driving shaft able to rotate inboth rotational directions; a sun gear driven by the driving shaft ofthe motor; a planetary gear, engaging with the sun gear, which canrevolve around the sun gear and rotate on its axis at a desired positionalong an orbital path taken around the sun gear; at least onetransmission gear, located along the orbital path of the planetary gear,which can engage with the planetary gear; and a locking member which canprohibit the planetary gear from revolving along the orbital path,wherein the locking member comprises a first locking member which canprohibit the planetary gear from revolving along the orbital path in oneorbital direction, the locking member further comprises a second lockingmember which can prohibit the planetary gear from revolving along theorbital path in another orbital direction, wherein at least one of thefirst locking member and the second locking member has a locking statein which the planetary gear is prohibited from revolving along theorbital path and an unlocking state in which the planetary gear isallowed to revolve along the orbital path, wherein a rotationaldirection of the motor at a time of revolution of the planetary gearalong the orbital path is reverse with respect to a rotational directionof the motor just before the revolution of the planetary gear along theorbital path.
 23. An actuating mechanism as claimed in claim 22, furthercomprising an actuator for switching the locking member between thelocking state and the unlocking state.